1. Technical Field
The present disclosure relates to a discharge lamp system. More particularly, the present disclosure relates to a discharge lamp system for projection and a method for controlling a discharge lamp.
2. Description of Related Art
In recent days, there have been a variety of projection apparatuses, such as Digital Light Processing (DLP) projection apparatus, LCD projection apparatus, Liquid Crystal on Silicon (LCOS) projection apparatus, etc., provided for different consumers. For a DLP projection apparatus, a discharge lamp is usually employed to generate the light for projection. In the DLP projection apparatus, a color filter (dynamic color filter) which is composed by a color wheel having three primary color segments, i.e., red (R), green (G) and blue (B), is used to filter the light from a light source, thus generating beams of three primary colors. A spatial light modulator is controlled synchronously and operated with the color filter to generate three primary color images so that color pictures can be shown. In the application that brightness is emphasized, a four-color dynamic color filter in which a white color (W) is added to the three primary colors R, G, B, is occasionally used to generate four-color images so that color pictures can be shown. Sometimes, more color segments are configured so that performance of color images can be enhanced.
However, for the four-color dynamic color filter, intrinsic properties of the color lights are different and requirements of brightness of the color lights are also different (e.g., one of the four colors has a different brightness from the others, or the brightness of a specific image area is different from that of the other image area), so intensity of light emitted by the discharge lamp is required to be different so that the current required by the discharge lamp has to be different as well. FIG. 1 is a diagram illustrating discharge lamp currents corresponding to the four color images generated by the four-color filter. As mentioned above, the current of the discharge lamp needs to be controlled so as to regulate the intensity of each color light, further achieving the purpose of projection.